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Full-Text Articles in Engineering
Development Of Techniques For Assessing And Restoring Streams On Surface Mined Lands, Whitney Cole Blackburn-Lynch
Development Of Techniques For Assessing And Restoring Streams On Surface Mined Lands, Whitney Cole Blackburn-Lynch
Theses and Dissertations--Biosystems and Agricultural Engineering
Surface mining is a commonly used method for extracting coal in the Appalachian Coalfields of the U.S. This mining practice produces excess spoil or overburden, which is often placed in adjacent valleys resulting in the creation of valley fills. These valley fills bury headwater streams, which in turn can negatively impact downstream ecosystems. In 2008, the University of Kentucky designed and constructed 1,020 m of ephemeral, intermittent and headwater streams on an existing valley fill (Guy Cove) as a proof-of-concept. The goal of the project was to evaluate whether or not a stream recreation could occur on mined lands, particularly …
Multifrequency Averaging Of Hysteresis-Current-Controlled Dc-Dc Converters, Yingying Liu
Multifrequency Averaging Of Hysteresis-Current-Controlled Dc-Dc Converters, Yingying Liu
Theses and Dissertations--Electrical and Computer Engineering
Multifrequency averaging is one of the widely used modeling and simulation techniques today for the analysis and design of power electronic systems. This technique is capable of providing the average behavior as well as the ripple behavior of power electronic systems. Hysteresis current control has fast response and internal current stability through controlling switches to maintain the current within a given hysteresis band of a given current command. However the state space variables in a hysteresis controlled system cannot be directly approached by multifrequency averaging method because of time varing switching frequency. In this thesis, a method of applying multifrequency …